Research progress on alkaloid acetylcholinesterase inhibitors from natural products / 中草药

Acetylcholinesterase (AChE) inhibitor is research hotspot for the treatment of Alzheimer’s disease (AD), which can be divided into two categories, chemical synthesis and natural products, according to its sources. Alkaloids are important sources of natural AChE inhibitors. In this paper, the research progress of plant-derived alkaloids with the inhibitory activity of AChE was reviewed from the aspects of structure type, mechanism of action and structure-activity relationship, in order to provide reference for the research and development of AChE inhibitors derived from natural alkaloids.

Advances in biosynthesis of galanthamine and huperzine A / 中草药

Acetylcholinesterase inhibitors (AChEIs) isolated from plants have become the mainstream of clinical treatment for Alzheimer’s disease because of their high efficiency and low toxicity. At present, the production of galantamine and huperzine A still mainly rely on plant extraction since they are not chemically synthesized on a large scale in industry. However, with the sharp rise of social demand, the contradiction between supply and demand has become increasingly prominent due to the difficulty in cultivation and the poor abundance of effective substances. Developing new alternative resources and taking the advantage of metabolic engineering for the production of AChEIs such as galantamine and huperzine are the efficient ways to alleviate the current contradiction. Here, the current development status of alternative resources was summarized and the progress of biosynthesis of galantamine and huperzine A during the past few years was reviewed.

Medication compliance in Singaporean patients with Alzheimer's disease

INTRODUCTION@#Singapore has a rapidly ageing population and an increasing prevalence of Alzheimer's disease (AD). Compliance to AD medications is associated with treatment effectiveness. We investigated compliance to acetylcholinesterase inhibitors (AChEIs) and N-methyl-D-aspartate (NMDA) receptor antagonist and treatment persistence among patients seen at the General Memory Clinic of National University Hospital, Singapore. We also identified the reasons for non-compliance.@*METHODS@#Patients seen at the General Memory Clinic between 1 January 2013 and 31 December 2014, who were prescribed AChEIs and NMDA receptor antagonist, were included in this retrospective cohort study. Non-compliance to medications was indirectly measured by failure to renew prescription within 60 days of the last day of medication supplied by the previous prescription. The reasons for non-compliance were identified.@*RESULTS@#A total of 144 patients were included. At one year, 107 patients were compliant to AD medications, while 37 patients were non-compliant. Around 60% of the non-compliant patients discontinued the use of AD medications within the first six months, and the mean persistent treatment period among this group of patients was 10.3 ± 3.5 months. The main reason for non-compliance was patients' and caregivers' perception that memory loss was of lower priority than other coexisting illnesses. Other reasons for non-compliance included side effects of medications (18.9%), perceived ineffectiveness of treatment (16.2%), inability to attend clinic (5.4%) and high cost of medications (2.7%).@*CONCLUSION@#Our findings suggest that the reasons for medication non-compliance can be identified early. Better compliance may be achieved through a multidisciplinary approach to patient education.

Rhodolirium andicola: a new renewable source of alkaloids with acetylcholinesterase inhibitory activity, a study from nature to molecular docking

ABSTRACT Acetylcholinesterase is an important target for control of neurodegenerative diseases causing cholinergic signaling deficit. Traditionally, galanthamine has been used as an Amaryllidaceae-derived acetylcholinesterase inhibitor, although new Amaryllidaceae plants could serve as source for better acetylcholinesterase inhibitors. Therefore, the objective of this study was to characterize the alkaloid composition from bulbs of Rhodolirium andicola (Poepp.) Traub, a native Chilean Amaryllidaceae specie, and assess their inhibitory activity on acetylcholinesterase by in vitro and in silico methodologies. Alkaloidal extracts from R. andicola exhibited an inhibitory activity with IC50 values between 11.25 ± 0.04 and 57.78 ± 1.92 µg/ml that included isolated alkaloid, galanthamine (2.3 ± 0.18 µg/ml), Additionally, 12 alkaloids were detected using gas chromatography-mass spectrometry and identified by comparing their mass fragmentation patterns with literature and database NIST vs.2.0. To better understand the bioactivity of isolated compounds and alkaloidal extracts against acetylcholinesterase, a molecular docking approach was performed. Results suggested that alkaloids such as lycoramine, norpluvine diacetate and 6α-deoxy-tazettine expand the list of potential acetylcholinesterase inhibitors to not only galanthamine. The role of R. andicola as a source for acetylcholinesterase inhibitors is further discussed in this study.

Acetylcholinesterase inhibitor insecticides related acute poisoning, availability and sales: trends during the post-insecticide-ban period of Anuradhapura, Sri Lanka

BACKGROUND@#Acetylcholinesterase inhibitor insecticides (AChEIIs) were used extensively in the agrarian region of Anuradhapura for the past few decades. As a result, the region faced a heightened risk of toxicity. Carbaryl, carbofuran, chlorpyrifos, dimethoate, and fenthion were the five hazardous AChEIIs banned from Anuradhapura in 2014. Assessment of post-ban trends in acute poisoning will reveal the impact of the ban. Data on availability and sales of remaining AChEIIs will guide towards preventive measures against related toxicities.@*METHODS@#Cross-sectional surveys were conducted at Anuradhapura district of Sri Lanka. Details related to acute AChEII poisoning were sorted from the Teaching Hospital Anuradhapura. Main insecticide vendors in Anuradhapura were surveyed to find information on availability and sales of AChEIIs. Chi-square for goodness of fit was performed for trends in acute poisoning and sales.@*RESULTS@#Hospital admissions related to acute AChEII poisoning have declined from 554 in 2013 to 272 in 2017. Deaths related to acute AChEII poisoning have declined from 27 in 2013 to 13 in 2017. Sales of all five banned AChEIIs had reduced by 100%. Sales of the remaining AChEIIs were declining, except for acephate, phenthoate, and profenofos. However, one of the top selling, most frequently abused carbosulfan, had the highest risk of toxicity. Chi-square for goodness of fit showed a significance (P < 0.001) between the trends of hospital admissions for acute AChEII poisoning and the sales related to AChEIIs.@*CONCLUSIONS@#Hospital admissions related to acute poisoning was declining along with the overall sales of remaining AChEIIs, during the post-AChEII ban period. Nevertheless, future vigilance is needed on the remaining AChEIIs to predict and prevent related toxicities.

A New Acetylcholinesterase Inhibitor from Green Glycosylation of Trachyloban-19-oic Acid by Mucor plumbeus

ABSTRACT The in vitro metabolism of a widespread natural product, trachyloban-19-oic acid (1), by the fungal species Mucor plumbeus was studied in a sucrose-yeast liquid medium. Two products were isolated, and their structures were determined by spectroscopic means as 7β-hydroxytrachyloban-19-oic acid (5) and trachyloban-19-O-β-D-glucopyranosyl ester (6). To the best of our knowledge, compound 6 is herein reported by the first time in the literature. These compounds were assayed for acetylcholinesterase inhibition along with some related compounds. Compound 6 showed the highest acetylcholinesterase inhibitory activity at 10000 µg/mL among the tested compounds, a result (92.89%) comparable to the activity of the positive control, galanthamine (94.21%). Therefore, biotransformation of the natural product 1 by M. plumbeus produced a novel compound with potential as a new lead to develop anti-Alzheimer medicines.

Inhibitory effect ofThymus vulgaris extract on memory impairment induced by scopolamine in rat

Objective:To investigate the effect ofThymus vulgaris (T. vulgaris) on learning and memory functions in scopolamine-induced memory deficit in rats. Memory enhancing activity in scopolamine-induced amnesic rats was investigated by assessing the Morris water maze and passive avoidance paradigm. Methods:A total of 42 male Wistar rats were divided into 6 equal groups as follow: control group: received water, scopolamine treated group: received scopolamine 1 mg/kg for 15 days, two scopolamine+T. vulgaris treated groups: received scopolamine andT. vulgaris extract 50 and 100 mg/kg body weight per day for 15 days, two intact groups: receivedT. vulgaris extract 50 and 100 mg/kg body weight per day for 15 days. Results: Administration ofT. vulgaris extract significantly restored memory and learning impairments induced by scopolamine in the passive avoidance test and Morris water maze test. Conclusions:T. vulgaris extract has repairing effects on memory and behavioral disorders produced by scopolamine and may have beneficial effects in the treatment of Alzheimer's disease.

Inhibitory effect of Thymus vulgaris extract on memory impairment induced by scopolamine in rat

Objective: To investigate the effect of Thymus vulgaris (. T. vulgaris) on learning and memory functions in scopolamine-induced memory deficit in rats. Memory enhancing activity in scopolamine-induced amnesic rats was investigated by assessing the Morris water maze and passive avoidance paradigm. Methods: A total of 42 male Wistar rats were divided into 6 equal groups as follow: control group: received water, scopolamine treated group: received scopolamine 1 mg/kg for 15 days, two scopolamine + T. vulgaris treated groups: received scopolamine and T. vulgaris extract 50 and 100 mg/kg body weight per day for 15 days, two intact groups: received T. vulgaris extract 50 and 100 mg/kg body weight per day for 15 days. Results: Administration of T. vulgaris extract significantly restored memory and learning impairments induced by scopolamine in the passive avoidance test and Morris water maze test. Conclusions: T. vulgaris extract has repairing effects on memory and behavioral disorders produced by scopolamine and may have beneficial effects in the treatment of Alzheimer's disease.

Design, synthesis and evaluation of new L-phenylalanine derivatives as acetylcholinesterase inhibitors / 中国药学杂志

OBJECTIVE: To research the effect of new L-phenylalanine derivatives on acetylcholinesterase (AChE) activity. METHODS: New L-phenylalanine derivatives were synthesized from substituted 2-bromo-l-acetophenones by four steps reaction, and their inhibitory activities on AChE were measured by Ellman method in vitro. RESULTS: The evaluation results showed that most derivatives possessed AChE inhibitory effect and the activity of compound 8b was the most potent with an IC50 value of 8.73 × 10-6 mol · L-1, which was more potent than that of rivastigmine; moreover, compound 8b had no inhibitory activities to BuChE. CONCLUSION: The inhibitory activities of new L-phenylalanine derivatives on acetylcholinesterase are worth studying further.

Research progress on plant-derived acetylcholinesterase inhibitory alkaloids / 中草药

Acetylcholinesterase (AChE) inhibitor is a research hotspot in the treatment of Alzheimer's disease (AD). According to the cholinergic hypothesis, the AChE inhibitors can increase the level of neurotransmitter acetylcholine in the brain, thus improving cholinergic functions in patients with AD and alleviating the symptoms of this neurological disorder. As AChE inhibitor is an important therapeutic strategy for AD, efforts are being made in the search for new molecules with anti-AChE activity. The fact that naturally-occurring compounds from plants are considered to be a potential source of new inhibitors has led to the discovery of an important number of AChE inhibitory alkaloids. Since the approval of galantamine for the treatment of AD patients, the search for new anticholinesterase alkaloids has escalated. This review summarizes recent advances in current knowledge on alkaloids as AChE inhibitors, and outlines the structure-activity relationship and docking studies.

Inhibition of acetylcholinesterase by two genistein derivatives: kinetic analysis, molecular docking and molecular dynamics simulation

In this study two genistein derivatives (G1 and G2) are reported as inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), and differences in the inhibition of AChE are described. Although they differ in structure by a single methyl group, the inhibitory effect of G1 (IC50=264 nmol/L) on AChE was 80 times stronger than that of G2 (IC50=21,210 nmol/L). Enzyme-kinetic analysis, molecular docking and molecular dynamics (MD) simulations were conducted to better understand the molecular basis for this difference. The results obtained by kinetic analysis demonstrated that G1 can interact with both the catalytic active site and peripheral anionic site of AChE. The predicted binding free energies of two complexes calculated by the molecular mechanics/generalized born surface area (MM/GBSA) method were consistent with the experimental data. The analysis of the individual energy terms suggested that a difference between the net electrostatic contributions (ΔE ele+ΔG GB) was responsible for the binding affinities of these two inhibitors. Additionally, analysis of the molecular mechanics and MM/GBSA free energy decomposition revealed that the difference between G1 and G2 originated from interactions with Tyr124, Glu292, Val294 and Phe338 of AChE. In conclusion, the results reveal significant differences at the molecular level in the mechanism of inhibition of AChE by these structurally related compounds.

Anticholinesterase activity evaluation of alkaloids and coumarin from stems of Conchocarpus fontanesianus

Conchocarpus fontanesianus (A. St.-Hill.) Kallunki & Pirani, Rutaceae, popularly known as pitaguará, is a native and endemic tree from São Paulo and Rio de Janeiro States, Brazil. Based in the information that anticholinesterasic derivatives could act as new prototypes to treatment of Alzheimer disease, this work describes the fractionation guided by evaluation of the anticholinesterase activity of the ethanolic stems extract from C. fontanesianus. This procedure afforded the alkaloids dictamnine (1), γ-fagarine (2), skimianine (3), and 2-phenyl-1-methyl-4-quinolone (4), as well as the coumarin marmesin (5).

Acetylcholinesterase inhibition by somes promising Brazilian medicinal plants / Plantas medicinais brasileiras promissoras para inibição da acetilcolinesterase

A microplate assay and a thin-layer chromatography (TLC) "in situ" assay based on the Ellman assay was used to screen for acetylcholinesterase inhibitors from ethyl acetate and methanol extracts of Brazilian medicinal plants of families that, according to the literature, have traditional uses that might be connected with acetylcholinesterase inhibition. Eighteen species belonging to Convolvulaceae, Crassulaceae, Euphorbiaceae, Leguminosae, Malvaceae, Moraceae, Nyctaginaceae and Rutaceae families were tested. The most active plants were Ipomoea asarifolia (IC50 = 0.12 mg/mL), Jatropha curcas (IC50 = 0.25 mg/mL), Jatropha gossypiifolia (IC50 = 0.05 mg/mL), Kalanchoe brasiliensis (IC50 = 0.16 mg/mL) and Senna alata (IC50 = 0.08 mg/mL). The most promising extracts were the Jatropha gossypiifolia and Senna alata species assuming there were compounds with a similar activity to galanthamine, which should contain about 1 percent of an active compound, or if present at lower levels even more active compounds than galanthamine (IC50 = 0.37 x 10-3 mg/mL) should be present.

Os ensaios de microplaca e cromatografia em camada delgada com base no ensaio de Ellman foram usados para triagem de inibidores da acetilcolinesterase dos extratos acetato de etila e metanol de plantas medicinais brasileiras de famílias que, segundo a literatura, tem usos tradicionais que podem estar relacionadas com a inibição da acetilcolinesterase, enzima associada ao mal de Alzheimer. Dezoito plantas das famílias: Convolvulaceae, Crassulaceae, Euphorbiaceae, Leguminosae, Malvaceae, Moraceae, Nyctaginaceae e Rutaceae foram testadas. As espécies mais ativas foram Ipomoea asarifolia (CI₅₀ = 0,12 mg/mL), Jatropha curcas (CI₅₀ = 0,25 mg/mL), Jatropha gossypiifolia (CI₅₀ = 0,05 mg/mL), Kalanchoe brasiliensis (CI₅₀ = 0,16 mg/mL) e Senna alata (CI₅₀ = 0,08 mg/mL). Os extratos mais promissores foram os das espécies Jatropha gossypiifolia e Senna alata, assumindo a presença de compostos com atividade semelhante à galantamina que deve conter cerca de 1 por cento de um composto ativo, ou se presentes em menores níveis ainda mais compostos ativos que a galantamina (CI₅₀ = 0,37 x10^–3 mg/mL) devem estar presentes.

Screening for antifungal, DNA-damaging and anticholinesterasic activities of Brazilian plants from the Atlantic Rainforest: Ilha do Cardoso State Park / Avaliação das atividades antifúngica, no reparo do DNA e anticolinesterásica de plantas brasileiras da Mata Atlântica: Parque Estadual da Ilha do Cardoso

Crude extracts from 17 plant species collected from an Atlantic Forest regionin the State of São Paulo (Brazil) have been screened for antifungal, DNA-damaging and acetylcholinesterase inhibiting activities. Of the 34 extracts obtained from leaves and stems ofplants assayed for antifungal activity with Cladosporium sphaerospermum and C. cladosporioides 26.5% were active. However, only the extract of leaves of Cabralea canjerana showed a stronginhibition of both fungi. The DNA-damaging assay with mutant strains of Saccharomyces cerevisiae resulted in 11.7 % of the extracts being active whereas 100% of them showedselectivity for the DNA-repair mechanism of topoisomerase II. Of the 17 species analysed, 12 showed anticholinesterasic activity in TLC assay. However, only extracts from Tetrastylidium grandifolium (stems) and Sloanea guianensis (leaves and stems) inhibited acetylcholinesterase activity more than 50% in quantitative assay.

Extratos brutos de 17 espécies de plantas coletadas em região de Mata Atlântica no Estado de São Paulo (Brasil)foram avaliadas para as atividades: antifúngica, no reparo do DNA e inibição da acetilcolinesterase. Dos 34 extratos obtidos de folhas e galhos das plantas analisadas para a atividade antifúngicacom Cladosporium sphaerospermum e C. cladosporioides, 26,5% foram ativos. Todavia, apenas o extrato das folhas de Cabralea canjerana inibiu fortemente o crescimento dos dois fungos. No ensaio de reparo do DNA com linhagens mutantes de Saccharomyces cerevisiae, 11,7% dos extratos foram ativos, sendo que, 100% destes foram seletivos para o mecanismo de reparo do DNA envolvendo topoisomerase II. Das 17 espécies analisadas, 12 demonstraram atividade anticolinesterásica no ensaio qualitativo sobre cromatografi a de camada delgada (CCD). No entanto, apenas os extratos de Tetrastylidium grandifolium (galhos) e Sloanea guianensis (folhas e galhos) apresentaram atividade anticolinesterásica maior que 50% no ensaio quantitativo.

Natural products inhibitors of the enzyme acetylcholinesterase / Produtos naturais inibidores da enzima acetilcolinesterase

Alzheimer's disease (AD) is a progressive, neurodegenerative pathology that primarily affects the elderly population, and is estimated to account for 50-60 percent of dementia cases in persons over 65 years of age. The main symptoms associated with AD involve cognitive dysfunction, primarily memory loss. Other features associated with the later stages of AD include language deficits, depression, behavioural problems including agitation, mood disturbances and psychosis. One of the most promising approaches for treating this disease is to enhance the acetylcholine level in the brain using acetylcholinesterase (AChE) inhibitors. The present work reviews the literature on plants and plant-derived compounds inhibitors of enzyme acetylcholinesterase. The review refers to 309 plant extracts and 260 compounds isolated from plants, which are classified in appropriate chemical groups and model tested, and cites their activity. For this purpose 175 references were consulted.

A Doença de Alzheimer (DA) é uma patologia neurodegenerativa, progressiva, que afeta principalmente a população idosa, responsável por 50-60 por cento dos casos de demência em pessoas com mais de 65 anos de idade. Os principais sintomas associado a DA envolve deficiência orgânica cognitiva, principalmente perda de memória. Outras características associadas com os estágios avançados de DA inclui déficit na linguagem, depressão, problemas de comportamento, inclusive agitação, alterações de humor e psicose.Um dos mais promissores caminhos para tratar esta doença é aumentar o nível de acetilcolina no cérebro usando inibidores da acetilcolinesterase (AChE). Este trabalho teve como objetivo revisar a literatura das plantas e substâncias encontradas nas plantas, inibidores da enzima acetilcolinesterase. Foram levantadas 309 plantas e 260 substâncias isoladas de plantas que foram classificados em grupos químicos adequados, os modelo testados, e suas atividades. Foram consultados 175 referências.